The indirect effects of radiation on biologically active macromolecules and their components are being studied and the action of individual radical intermediates related to specific chemical changes. Chromatin extracted from Chinese hamster lung fibroblasts is being examined for radiation damage in the component DNA and chromosomal proteins and in the DNA-protein interactions. The formation of radiation-induced DNA-protein cross links in chromatin is being studied and the specific histone and non-histone protein fractions involved in the cross linking identified. It is proposed to use SDS-polyacrylamide gel electrophoresis to characterize the histone proteins and to determine protein-protein cross linking. Changes in DNA-protein interactions will be monitored by the use of probes, such as, nuclease digestion and polylysine titration. Damage to histone and non-histone proteins will be examined by amino acids analysis, and strand damage in DNA determined by sedimentation on sucrose gradients. In addition, the action of amino acid radicals and alcoholic radicals on peptides and proteins will be studied. Changes in the amino acid composition will be measured and the degree and sites of association of the amino acid and alcoholic radicals determined.